The report, Whole of Government Accounts (WGA) for 2009-10, also says that the Treasury was "surprised" to learn that £10.9 billion of unpaid tax had been written off by HM Revenue & Customs in one year.

“Claims for clinical negligence outstanding at 31 March 2010 could cost £15.7 billion, or 15 per cent of the government’s total provision for future expenses arising from events that have happened in the past,” the report warns.

“The Treasury … did not know that clinical claims recorded by the NHS Litigation Authority had increased by some 31 per cent in 2010/11 or what plans were in place to reduce liabilities for clinical negligence.”

A large proportion of the clinical negligence bill is the result of errors that have left babies brain damaged – an area where the cost is rising as advances in medicine mean these children live longer and therefore cost more.

However, successful cases brought through “no win, no fee” lawyers also account for a substantial chunk as they demand higher fees to cover their bills in lost cases.

Last year, more than 8,500 clinical negligence claims were received by the NHS, an increase of more than 30 per cent on 2009/10.

This clinical negligence bill is a calculation, based on the number of claims the NHS believes it will not be able to defend, the severity of the claimed errors and how much a victim would be paid out for these mistakes.

It therefore includes an estimate of the cost of mistakes that have not yet been claimed for.

Officials admit that the £15.7 billion compensation bill could be an underestimate if the NHS loses more cases than predicted.

A spokesman for the Department of Health said: “The vast majority of the millions of people treated by the NHS every year experience good quality, safe and effective care.

“However, if patients do not receive the treatment they should, and mistakes are made, it is right that they are entitled to compensation and the NHS Litigation Authority plays a vital role in ensuring claims are settled as swiftly as possible.

“The Government’s ambitious proposals for reforming the civil litigation system will support the NHS in dealing with costly litigation cases.

“We want to strike the right balance between access to compensation claims and ensuring costs are proportionate, sustainable and affordable.”

The WGA report, which was compiled and published for the first time last year, highlights areas where the Government’s understanding of spending was “poor”.

"For instance the Treasury showed surprise at the estimated £10.9 billion in outstanding tax and it had no knowledge of recent trends in clinical negligence claims or whether plans were in place to reduce the estimated £15.7 billion cost to taxpayers of meeting these claims," the MPs said.

"The Treasury should use the WGA specifically to identify key risks to public funds and ensure bodies included in the WGA can demonstrate that they are addressing them effectively."

The report added: "We were surprised to find that Treasury did not have a grip on trends in some key areas of risk or plans for managing them."

The report also highlighted massive swings in liabilities for public sector pensions and nuclear decommissioning, partly due to officials' "inconsistent" use of discount rates when calculating the figures.

The Treasury said the WGA represented "the most ambitious public sector account prepared anywhere in the world" and that it was working hard to remove the qualifications.

"No other country has sought to fully consolidate all public sector bodies, including the local government sector, in one statement of accounts. We will build on this first publication and are working hard to remove any qualifications," a spokesman said.

"HMRC collects almost all tax debt and write-offs are relatively low. What's more, around 90% of those write-offs are due to insolvency where further debt pursuit is actually barred by law."

The spokesman added that the Government had for the first time published a clear assessment of PFI liabilities and launched a review which would "mean the end of PFI as we know it".